1. Field of the Invention
The present invention relates to a compound which is soluble in an alcohol or alcohol type solvent and has a good electron transferring capability. More particularly, the present invention relates to an alcohol soluble electron transferring compound soluble, and to an electrophotographic photoreceptor having improved electric and magnetic properties. The invention is also directed to an electrophotographic photoreceptor having an undercoating layer or a photoconductive layer containing an alcohol soluble electron transferring compound.
2. Description of the Related Art
An electrophotographic photoreceptor is used in electrophotographic image-forming apparatuses, such as facsimile machines, copiers, laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser electrophotographic devices. Basically, in an electrophotographic image-forming apparatus, a photosensitive material is electrified and exposed to an image-forming light source to form an electrostatic latent image. Then, the image is developed with toner (also referred to as ink) by applying a developing voltage. The toner image is then transferred to a recording medium such as paper, and the image is fixed thereon.
The electrophotographic photoreceptor includes a photoconductive layer containing a charge generating material (CGM) and a charge transferring material (CTM) on an electrically conductive substrate. Generally, the electrophotographic photoreceptor contains an additional functional layer. In one example, an undercoating layer is formed between the electrically conductive substrate and the photoconductive layer. In other examples, a protective layer is formed on the photoconductive layer.
The function of the undercoating layer is to improve the adhesive property between the conductive substrate and the photoconductive layer and prevent the hole injection from the conductive substrate to the photoconductive layer. Also, the undercoating layer allows easy electron transfer from the photoconductive layer.
An anodic oxidation layer of the electrically conductive substrate can be used as an undercoating layer. The undercoating layer can also be formed by preparing a coating liquid containing a polymer resin such as polyamide resin, and applying the coating liquid on the conductive substrate.
The anodic oxidation layer of the conductive layer is widely used as the undercoating layer. However, the cost is high, and thus the manufacturing cost of electrophotographic photoreceptor is increased.
When the undercoating layer contains a polymer resin, it is advantageous to have the undercoating layer as thick as possible to prevent the hole migration from the substrate to the photoconductive layer. However, as the thickness of the undercoating layer increases, the electron migration from the photoconductive layer is also reduced or prevented, and thus, the exposure potential is increased. In order to solve these problems, methods of providing an undercoating layer containing an electron transferring material have been researched.
U.S. Pat. No. 5,141,837, U.S. Pat. No. 5,589,309 and U.S. Pat. No. 5,815,776 disclose an electrophotographic photoreceptor having an undercoating layer containing a perylene compound represented by the following Formula 1 as an electron transferring material.

Since the perylene compound disclosed in the above-mentioned patents is insoluble in alcohol, it is used in the form of pigment dispersed in a polymer resin. However, electrons can not flow through the pigmented perylenes disclosed in the above-mentioned patents, and thus the electron transferring capacity is inferior.
In order to solve these problems, the electron transferring material contained in the undercoating layer should be soluble in the solvent used in the undercoating layer. In this regard, because solvents usually used in photoconductive layers are non-alcohol type solvents, the binder resin of the undercoating layer should be limited to materials that are soluble in alcohol type solvents in order not to be dissolved in the solvent of the photoconductive layer. In addition, alcohol type solvents in which this binder resin can be dissolved are used as the solvent of the undercoating layer. Therefore, the electron transferring material contained in the undercoating layer should be a material which can be dissolved in alcohol type solvents. However, there is no material in the prior processes that satisfy this need.